Sometimes, I really get sick of humans. But seeing this reminds me that, despite our faults, we really are a great animal. What other animal goes out of its way to help other animals live the best possible life? Go humans!
It`s a symbiosis mostly though. I mean the fungi bacteries etc. that you have mentioned. Also, cats dogs and so on help (MOSTLY AGAIN :D) to the other dogs and cats.
But of course there are cases when a dog bitch has raised little tigers, which although has happened thanks to humans.